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Lewy Body Dementia: Diagnosis


Lewy body dementia (LBD) is an emerging disease, in terms of ability to define and diagnose it. It’s increasing in frequency, and/or in the medical community’s ability to identify the condition. LBD is thought to be the third most common dementia, after Alzheimer’s dementia and vascular dementia. More resources are being allocated for more research, dedicated to greater understanding of the condition and its management.

Dementia is a general term, describing a wide range of signs and symptoms, applied to deterioration in thinking severe enough to interfere with daily living. Functioning declines gradually – slowly for some, but too quickly for too many, their loved ones and caregivers. The ability to work is affected or work is no longer possible. Dementia steals independence, and the ability to manage financially or perform personal care.

Lewy bodies are abnormal clumps of a protein called alpha-synuclein, which form in the brain. Clumps in the cortex of the brain affect thinking. The protein is found throughout the brain, but its normal purpose is not yet known. Lewy bodies were named after Frederick H. Lewy, MD, a neurologist working in the lab of Dr. Alois Alzheimer’s laboratory in the early 1900s.

Types of Lewy Body Dementia (LBD)

There are two types of Lewy Body Dementia – dementia with Lewy bodies and Parkinson’s disease dementia. It’s essential to determine which type of LBD a person has, to determine the proper treatment for particular symptoms and to know what an individual can expect in the future. There is a “1-year-rule” used by practitioners and researchers to differentiate a patient’s type of LBD. If cognitive symptoms appear within a year of movement symptoms, the diagnosis is dementia with Lewy bodies. If cognitive problems develop more than a year after the onset of movement symptoms, the diagnosis is Parkinson’s disease dementia. Dementia with Lewy bodies may progress more quickly than Parkinson’s disease dementia.

LBD is often hard to diagnose because its early symptoms may resemble Alzheimer’s disease, Parkinson’s disease, or a psychiatric illness. It is often misdiagnosed or completely missed. As more symptoms occur, it becomes easier to make an accurate diagnosis. Physicians are becoming more skilled at diagnosing LBD earlier and with increased accuracy as researchers discover which symptoms help distinguish it from similar diseases.

Early Diagnosis

An accurate diagnosis, as early in the course of the disease as possible is important to providing the right medical care while avoiding potentially harmful treatment. It allows for more time to plan medical care and arrange financial and legal matters. Early diagnosis gives time to assemble a support team to manage the condition, to maximize quality of life and retain as much independence a possible.

Some people are relieved to know the cause of their symptoms, even though it can be distressing to receive the diagnosis. It allows the individual to participate in the planning for their own care as the disease progresses.

Tests used to Diagnose LBD

An evaluation may include:

  • Medical history and examination to review old and current diagnoses and medications, as well as previous test results, especially movement and memory tests
  • Laboratory studies to evaluate for other diseases, as well as nutritional and hormonal problems that can be associated with dementia
  • Brain imaging, such as computed tomography (CT) or magnetic resonance imaging (MRI) which can detect structural abnormalities and brain shrinkage, as well as help to rule out other causes of symptoms
  • Neuropsychological tests which assess memory, various types of thinking, and help identify the affected regions of the brain.

There are no imaging or laboratory tests that can definitively diagnose LBD. It’s diagnosed with certainty only by brain autopsy after death.




Neef D, Walling AD. Dementia with Lewy bodies: An emerging disease. Am Fam Physician. 2006 Apr 1;73(7):1223-1229

National Institute on Aging, National Institutes of Health. Lewy Body Dementia: Information for Patients, families and Professionals. 2015 Sep 15. https://www.nia.nih.gov/alzheimers/publication/lewy-body-dementia/diagnosis


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